Vehicle titles and tags are issued by the states and rules and fees will vary, often substantially. And insurance requirements and costs will vary by the state in which it is tagged, so they are somewhat tied together. You may find that Florida is easier to tag & title the vehicle and I suspect that fees and taxes will be less than most other southeastern US states as well. Florida, with a large seasonal transient population, is accustomed to dealing with vehicle tags for people who are there only temporarily, plus a lot of visitors buy RVs in Florida. A Florida tag & title will likely cost under $100 but you will have to pay sales tax (about 6%) on the purchase price of the motorhome unless you already paid that in Georgia. In most states, the taxes are collected when the tags are purchased, though.
Insurance requirements vary by state but Florida does not have onerous requirements. You should carry liability insurance, though, in case you damage someone or something in an accident. As for insuring your Pathfinder against damage to it (accident/fire/theft/etc.), that is up to you and is a cost vs risk assessment. As a visitor to the US, you may have some difficulty finding an insurer and rates are typically much higher for non-residents who do not have a US driving license, i.e. are using an international license.